LANDOVER, Md. — There was just 4:42 remaining last night, the Giants facing a must-convert third-and-10. They were at their own 43-yard line, trailing by a point.

Eli Manning fired an 11-yard completion to Martellus Bennett, keeping the drive going and bringing the ball past midfield to the Washington 46. The Giants were maybe 10-to-15 yards away from go-ahead field goal territory.

Problem was, tackle Will Beatty ended up being called for holding on Bennett’s catch. No first down at the Washington 46. Instead, it was third-and-20 from the Giants’ 33. And one play later, the Giants ended up punting and never got the ball again.

“You convert it,” Beatty said of that third down, “it changes a lot.”

The Giants ended up losing 17-16 to the Redskins at FedEx Field, a possible division-changing defeat. And it was a brutal night for the Big Blue offensive line. Beatty’s penalty was the ultimate crusher, but it went beyond that. Backup lineman Jim Cordle committed two holding penalties on kick returns, one wiping out a 49-yard David Wilson return on that same Beatty drive that would have put the Giants at midfield to start the drive.

Instead, they started at their own 8-yard line.

“Every time we had a kickoff return, we had a penalty,” coach Tom Coughlin said.

The Giants also had a false start penalty on right tackle Sean Locklear on their first drive of the night, helping to limit them to a field goal instead of a potential touchdown. And they lost Locklear in the fourth quarter to what appeared to be a bad and probable season-ending knee injury, damaging their depth. With Locklear out, David Diehl returns to right tackle. But the Giants lose a key reserve. Their backup tackle is now James Brewer.

“The good thing is David’s healthy again,” guard Chris Snee said, “and we need other guys to step up and fill roles.”

Beatty didn’t step up last night on his holding penalty. He wasn’t sure what the problem was.“It wasn’t a pulldown,” he said. “It wasn’t a yank.”

Either way, it was minus-21 yards on the net.

“That was a big situation for us in the game,” Bennett said. “We didn’t need a penalty right there.”